High-low gravity tank alarm float



Dec. 29, 1931. I H E 1,838,135

HIGH LOW GRAVITY TANK ALARM FLOAT Filed June 26, 1928 ATTORA EY Patented Dec. 29, 19,31

PATENT OFFICE JOHN H. DERBY, OI SCARSDALE, NEW YORK HIGH-LOW GRAVITY TANK ALARM FLOAT Application filed June 26,

This invention relates to alarms and signal devices such as are employed for giving an indication of the level of liquid in a; tank.

It is an object of the present invention to provide a simple and reliable device for giving a si nal when the level of llquld in" a tank is a mined levels.

Another object of the invention is to pro-. tect various parts of the device from corrosion or injury. a t

The invention will be. more clearly understood by reference to the accompanying figve or-below certain predeterure of the drawing which illustrates a preferred embodiment of the invention.

The figure is a diagrammatic view of the apparatus.

In the form of the device as illustrated a float 1 is located in the tank and is preferably in the form of a hollow cylindrical chamber formed of light metal, such as brass or bronze tubing tinned or chromium plates to resist corrosion. The float 1 is provided with a central opening .2'through which a hollow Monel metal rod 3 passes so that the float is free to move up or down u on the rod 3 as a guide. This rod is rovi ed with a stop 4 to limit the downwar movement of the float member and is provided with a stop 5 to p'revent upward movement of the float member beyond predetermined points. The rod 3 passes through a heavy tubular member 9 supported by the bracket 10 and secured thereto b means of the cast iron bushing 11 and'a lock nut 12. A guide 8 is located in the lower end of the member; 9 .and is preferably in the form of a bakelite bushing threaded into. the tubular member 9 as shown. The

red 3 extends above the member'9 and into a casing 15 containing the signal means, to be hereinafter described. A second ide 16 in the form of a bakelite bushing t readed into the upper end of the tubular member 9 'is also provided. The'rod 3 preferably car- 'vided with a slot 24 in order ,central portion with a bracket 35 1928. Serial No. 288,388.-

vided with upper and lower eng 'n 17 adapted to engage a bakelite b us ing 18 whichis slidable on the rod 3. The bushing 18 has a reduced central portion 19 which is engaged by the forked ends 20 of a bronze operating bar 22. The bar 22 is ivoted about the bearing 23 and is provide at its opposite endwith a slot 24 engaged by the springs 26. and 27. The lower s rm 26 acts as a counterbalance for the weig t o the rod 3 and the elements secured thereto while the upper spring 27, when tensioned, urges the operating bar 22 back to its normal position. The sprlng 27 is preferably adjustable by means of the threaded member 29 sup orted by the bracket 30 securedto the caslng 15 and is normally slack so that the balance of I the rod 3 and its associated parts will not be destroyed by splashing of the mercury in the chamber 22 or by jarring of the tank or the casing 15. The operating bar 22 is prothat a very small amount of play ofthe spring 27 may take place.

The operating bar 22 is provided at its to which spring clips 36 and 37 are secured. A glass blocks chamber 38 containing a-conducting liquid such as mercury, is mounted in the spring clips 36 and 37 and is provided with three spaced contact members which form a. part of an electric circuit to be used'in giving an alarm when the level of the liquid in the tank is greater or less than the predeter mined levels. The central contact 40 may be termed a common and is continually submerged or in 'contact with the mercury in the chamber 36. The end contacts 41 and 42 are positioned slightly above the level ofthe mercury in the tube so as to be out of contact with the mercury when the tube 36 is in its normal position butin position to complete a circuit through the mercury and the common ivvhenever the chamber 38 is tilted by as movement ofthe operating bar 22. If a closed .alarm circuit is employed the contacts 40,

41 and 42 may all be in contact with the mertilting of the chamber by the operating v rod 22.

In the construction shown the contacts 40, 41 and 42 are connected to resistances 52 or up other elements of the signal circuit and the circuit elements are connected to the terminal box 53 mounted on the upper part of the casing 15. The cover may then e fixed to the casing by sealed screws or other means to w prevent tampering with the circuit or alterin its adjustments. Ihe signal circuit and re ated elements may be of any desired ty e such as those shown and described in t e applicants Patent. No. 1,536,192May 5, 1925.

In orderto revent corrosion of the various parts of t e mechanism and to prevent the access of vapors from the tank "to the casing 15 where they might cause corrosion go of the various parts, a cylindrical. casing 50 is provided supported by the bushing 11 and extending downwardly from the bracket below the level of the liquid in the tanlr,

The casin 50 is preferably formed of brass g5 tubing an is of shghtl larger diameter than the float member 1. he casing 50 prevents the passage of vapors from the tank through the bushings 8 and 16 into the casing and limits the area from which the vapors could rise to the very small surface of the liquid betweenthe float 1 and the casing 50. In order to further insure that no corrosion of the parts enclosed in the casing 15 me. occur the-space 51 between the rod 3 an the tubular member 9 may be filled with wool or other moisture-absorbin material. If desired, a small vent 53 may he provided in the u per end of the casing 50 to permit the air displaced by movement of the piston and the liquid within the casing 50 to pass into and out of the casing.

The casing 50 performs several ,very imortant functions besides limiting the sur ace area from which vapors can arise to.

corrode the parts of the mechanism. Thus, it is seen that if the liquid in the tank should be set in motion by a pump or tor any other reason, the float 1 will not be affected by the currents produced in the tank but will float on the undisturbed liquidvwithin the casing and give an accurate indication of the level of the liquid in'the tank. The casing also limits the lateral movement pf the float member 1 'and prevents it from bum ing against the rod 3 and giving a false in icetion of the level of the'liquid in the tank.

The casing 50 member during shipment of the mechanism so as to prevent damage or bending of the rod 3.

The operation of the device is as follows:

- The stop members the desired positions and secured in place. The spring 26 is adjusted so as to balance the rod 3 and the spring 27 adjusted until it is ,cury

also acts as a protecting to the float member 4 and 5 are adjusted to ,2. A device as defined in claim 1,

under no tension when the operating bar 22 is horizontal or in the desired position. The casing 15 then the level so that the float does not bear against either stop but if the level of the liquid should become too low the float 2 will bear against the stop member 4 or 5 no alarm will be given may then be sealed shut. If. of the liquid in the tank varies v 4 on the rod 3 and instead of being submerged in the liquid in the tank to a normal depth it will be en ported .by the rod 3 so that the balance 0 the mechanical system willbe destroyed, tilting the operating rod 22 and chamber 38 so that the contact member 422 will make contact with the mercury, or if a closed alarm circuit is used the contact ll will break its contact with the mercury and an alarm will be given, indicating that the level of the liquid in the tank is below the predetermined level.

Un the other hand, if the level of the li uid in the tank should become too high. the oat will engage the stop 5 and be submerged beyond the normal depth, causing the rod 3 to be moved upward, tilting the operating bar 22 and giving the desired signal,

From the foregoing description it will be seen that a simple level indicator is provided which is sensitive and so protected from cor rosion and deterioration that it may be safely and effectively used for long periods of time without adjustment and on tanks such as emergency water tanks which are not subject to frequent inspection.

What is claimed as new is:

l. A signal device responsive to li uid lev el, which com rises a float, a vertic casing surroundin tile float so as to protect it from local distui bances in the liqfiid, but open to the tank above and below t e float so as to permit said float to respond accurately to changes in the general level "of the liquld, a mercury switch connected into a circuit so as when closed to give a high level alarm, a merswitch connected into a circuit'so as to give a low level alarm, means connecting said float to said mercury switches adapted to tilt the high level alarm switch so as to close its contacts when the float is raimd to a position corresponding to a liquid level at the u per limit of permissible variation, and to t t the low level switch so 'iio tion corresponding to a liquid level at the lower limit of permissible variation, means for resiliently maintaining said switches in a open contact position while said float is between said limiting positions adapted to yield to theforces exerted by the float at said limiting positions, and a housing en closing avspace about said switches, said housin being substantially airtight except fora c osely fitting opening said connecting means extends.

through which in wh ch n the opening for the connecting means is protected by a substantially uncompressed packingof a moisture-repellant fibrous material.

' 3. A device as defined in claim 1, in which the opening for the connecting means is protected by a substantially uncompressed packing of Wood.

Signed at New/York, Y., this 21st day of June 1928.

' JOHN H. DERBY. 

